1. Field of the Invention
The present invention relates to a housing and a display device provided with the housing, and more particularly to a housing that is preferable for use in a display device having display face on both the front and back faces and a double-sided display device provided with the housing.
2. Description of the Prior Arts
A flat-type display device such as a liquid crystal display device or plasma display panel or the like has spread as a display device, wherein its size has been increased. The following explanation is made by taking a liquid crystal display device as one representative example of such a flat-type display device. The liquid crystal display device has widely been used as a monitor for office automation equipment or television because of its feature of being compact, being thin-sized and providing reduced power consumption. The liquid crystal display device is classified into a directly-beneath type (reflection plate type), edge-light type (side-light type) or surface light source type. A directly-beneath type is mainly used for a monitor that requires high brightness. This liquid crystal display device of the directly-beneath type is provided with a liquid crystal panel 6 having liquid crystal sandwiched between opposing transparent substrates, and a substrate 7 connected to the liquid crystal panel 6 via a tape carrier package (TCP) 8 as shown in FIG. 1. The liquid crystal display device is further provided with a backlight device 2 that produces backlight for illuminating the liquid crystal panel 6 and a housing 4 (shield front) for supporting these components.
As shown in FIG. 2, the backlight device 2 is provided with plural bar-like lamps 10 serving as a light source, an inverter substrate 12 or return substrate 13 for supplying power source to the lamps 10 and a return cable 14 (power source circuit section) for connecting these substrates. Moreover, the backlight device 2 is provided with a lamp support frame 11, a reflection plate 15, an optical member comprised of a diffusion plate 18 or optical sheet 19 and a backlight chassis 20 (housing)
Further, a double-sided liquid crystal display device having display face on both the front and back faces has recently been developed. This double-sided liquid crystal display device is provided with a double-sided backlight device 3 for irradiating backlight in both directions of the front face and back face as shown in FIG. 3. A pair of liquid crystal panels 6A and 6B are mounted on each face of this double-sided liquid crystal display device. Substrates 7A and 7B are joined to the liquid crystal panels 6A and 6B via TCP 8A. Housings 4A and 4B (shield front) hold each liquid crystal panel 6A and 6B to the double-sided backlight device 3.
The double-sided backlight device 3 is formed such that its front and back are symmetric so as to be capable of irradiating backlight from both front and back faces; For example, the double-sided backlight device 3 is provided with plural bar-like lamps 10 serving as a light source, an inverter substrate 12 for supplying power source to the lamps 10 and a power source circuit section such as a return cable 14 as shown in FIG. 4. The lamps 10 are nipped to be held by lamp support frames 11A and 11B from both front and back faces. Further, the double-sided backlight device 3 is provided with a reflection plate 17, an optical member comprised of diffusion plates 18A and 18B and optical sheets 19A and 19B, and backlight chassis 20A and 20B (housing of the backlight). The reflection plate 17 reflects light from the lamps 10 toward the liquid crystal panel. An example of the double-sided liquid crystal display device as described above is disclosed in Japanese Published Unexamined Patent Application No. 2001-290445.
A liquid crystal display device has a great number of components as described above. For facilitating the assembling, the liquid crystal panel or backlight device is formed as a unit. These units are supported and fixed en bloc by a housing. When a screen size of the liquid crystal display device is increased, its frame is narrowed and its size is thinned, the width of the frame section of the housing and the width in the thickness direction of the liquid crystal display device are reduced, whereby load applied to the housing is increased. Further, in order to realize reduced cost of the liquid crystal display device, it is required not only to reduce the cost of each unit but also to reduce the cost of the housing itself. Moreover, it also becomes important to facilitate the assembling of the housing and unit, thereby reducing assembling manhour.
In a conventional liquid crystal display device, a general configuration is such that a housing for holding each unit is generally comprised of a frame member having a large size and a frame member having a small size, and this pair of frame members each having a different size are fitted to each other to hold each unit. For example, each unit is held by the combination of the housing 4 and the backlight device 2 in FIG. 1 and the combination of the backlight chassis 20A and the housing 4A and the combination of the backlight chassis 20B and the housing 4B in FIG. 3. The conventional housing structure as described above involves the following problems.
The first problem is that the strength of the entire liquid crystal display device 1 cannot sufficiently be maintained. Specifically, a frame member is generally manufactured by bending a sheet metal, so that the side face of the frame member is formed by a flat plate. Consequently, it is structurally weak with respect to external force, thereby being easy to be deformed. In particular, the width of the frame and the width of the side face are decreased as the screen size is increased and the size of the frame and thickness are decreased, thereby unable to assuredly hold each unit.
Moreover, the second problem is that the housing is difficult to be assembled, so that the deterioration in display quality caused by assembling failure is likely to occur. Specifically, in the structure wherein a great-sized frame member is fitted to a small-sized frame member so as to cover the small-sized frame member, both frame members are prone to tilt during the fitting process, so that the assembling process requires practice. Further, when the frame members are fitted as they are tilted, the position or space of each unit is shifted, resulting in deteriorating display quality. This second problem appears more conspicuously with the increased screen size, narrowed frame and thinned size.
Additionally, the third problem is that, when frame members of plural types each having a different size are combined, frame members of plural types should separately be manufactured, thereby being unable to provide a reduction in cost. Normally, the frame member is manufactured by processing a sheet metal with the use of a mold. In order to prepare frame members of plural types, plural molds should be prepared. Therefore, design cost or processing cost may be increased. Further, in the structure wherein frame members of plural types are combined, these frame members should separately managed, thereby also increasing managing cost.
Moreover, the fourth problem is that, in the structure wherein frame members each having a different size are combined, a difference occurs in the appearance between the front and back, which makes the device bad-looking. From the viewpoint of design, it is important in the double-sided liquid crystal display device that the appearance looks same even seen from the front side or back side.
These problems occurs on not only a liquid crystal display device but also on a display device of any type at least holding a display panel by using a housing.